Rheological behaviors and mechanical properties of kenaf-polypropylene composites / Amirul Hafiz Johari

This project is carried out to study the mechanical and rheological properties of kenaf powder reinforcement with polypropylene (PP). The effects of incorporating coupling agent which is maleic anhydride grafted polypropylene (MAPP) at 3wt% to the strength and toughness of the composite were investigated. The size of the kenaf powder was selected is limited to 150|im with the different kenaf ratio of 10 wt%, 20 wt%, and 30 wt% kenaf; with and without MAPP, mixed with polypropylene and compounded using hot press machine. Tensile and flexural tests were performed to evaluate the tensile and flexural properties. The composite with 30% of kenaf with MAPP exhibited the highest tensile stress, flexural stress and modulus. Tensile and flexural properties were enhanced with the addition of kenaf powder. However, the sample with MAPP gave the higher strength than the sample without MAPP. The rheological behavior of the compounding material was analyzed using capillary rheometer at a range of temperature allowed investigation of the relationship between pressure, volume, and temperature. The rheology analysis of kenaf-polypropylene exhibited that 30 wt% kenaf having the higher viscosity than other percent of kenaf at operating temperature of 190°C. Fracture surface observation revealed that the failure mainly due to fiber delamination in addition to ductile failure of PP. However, to compete with glass fiber effectively, further research is needed to improve natural fiber processing.